Conventionally, in an electrophotographic image forming apparatus using an electrophotographic image forming process, a photosensitive drum and process means actable on the drum is unified into a cartridge. The cartridge is detachably mountable to a main assembly of the electrophotographic image forming apparatus (process cartridge type). According to the process cartridge type, a maintenance operation for the image forming apparatus can be carried out by the user without relying on a service person, and therefore, an operationality of the maintenance operation can be improved remarkably.
A method is known in which a coupling member is provided at an end portion of the drum to rotation the drum, and a driving force is inputted to the coupling member from the main assembly of the apparatus. With such a structure, it is known that the coupling member is movable relative to the drum so that even if a positional relation between the cartridge and the main assembly of the apparatus is deviated, the drive can be transmitted to the drum with high accuracy (Japanese Laid-open Patent Application 2008-233867).